Category Archives: Oral Pathology

Glandular odontogenic cyst

Oral Pathology

Common site

  • 80% anterior mandible
  • Anterior maxilla

Clinical

  • Jaw expansion

Histology

  • Non keratinized epithelial lining + mucous cells
  • Resembles salivary gland tumor – mucoepidermoid tumor

Radiology

  • Unilocular/multilocular with well defined sclerotic border

Management

  • Surgical enucleation

Gingival cyst

Oral Pathology

Newborn/infants:

Pathogenesis

  • Dental lamina remnants – proliferation – small keratinized cysts

Common in neonates

Clinical

  • Small swellin on alveolar mucosa
  • Varying color: White – grey white – yellow

Prognosis

  • Not harmful, break up by themselves

Adult:

Pathogenesis

  • Dental lamina remnants
  • Implantation of epithelia during gingival treatment procedure

Clinical

  • Uncommon
  • Small
  • Uninflammatory
  • Gingival swelling
  • Bluish color

Common site

  • Mandible

Management

  • Excisional biopsy

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Lateral periodontal cyst

Oral Pathology
  • Rare intraosseous of intrabony development cyst
  • Form besides vital tooth

Pathogenesis

  • Dental lamina

Clinical

  • No symptoms
  • Erodes through bone into gingiva

Common site

  • Lateral surface of root of vital tooth
  • Mandibular premolar/canine region
  • Size < 1cm diameter

Radiology

  • Unilocular
  • Round/oval
  • Well defined
  • Corticated
  • ± Sclerotic margin

Histology

  • Squamous/cuboidal epithelium
  • 1-2 cell thick + focal thickenings

Management

  • Enucleate cyst and retain healthy tooth

Complications

  • Strong tendency to recur
  • Sporadic bud-like proliferation after enucleation

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Eruption cyst

Oral Pathology

Fluid accumulates in follicular space

Clinical

  • Bluish swelling occurring in soft tissues
  • Usually found in children

Histology

  • Fluid in cyst usually clear, may contain blood – eruption hematoma
  • Keratinized epithelium of alveolar ridge
  • Thin uninflamed fibrous tissue lining the cyst

Management

  • Tooth erupts and cyst disappears, no treatment required
  • If necessary (parental concern) – surgical enucleation
  • Small epithelial incision

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Keratocystic odontogenic tumor (KCOT)

Oral Pathology

Incidence

  • 2-3rd decade

Common site

  • 70 – 80% mandible especially 3rd molar and ascending ramus region

Pathology

  • Rests of dental lamina

Pathogenesis

  • PCTH tumor suppressor mutation
  • High epithelial proliferation (Ki67+ve)
  • Apoptosis evasion by increased Bcl2
  • Over expression of interface proteins:

Clinical

  • Painless
  • Slow growing expansile intraosseous mass
  • Discovered on routine x-ray
  • Grow in anterior – posterior direction. Reach large sizes without gross bony expansion

Clinical subtypes

  • Solitary lesion
  • Multiple lesions
  • Syndrome associated lesion: Gorlin Goltz syndrome
    • Therefore do full body check up

Histology

  • Cyst wall:
    • Fibrous
    • Thin and corrugated/ folded
    • Contains daughter/satellite cyst
  • Epithelial lining:
    • Flat basement membrane
    • Hyaline/Rushton bodies
    • Keratinized squamous epithelium
    • Lack rete pegs
    • Thin and even thickness, < 10 cells thick
  • Lumen:
    • Straw colored fluid (keratin)
  • Basal cells Ki67 and Bcl2 positive – shows high mitotic figures

Radiology

  • Unilocular/multilocular radiolucency, some with impacted teeth
  • Well circumscribed radiolucency with radiopaque margins

Biopsy

  • Aspirational biopsy:
    • Greasy fluid
    • Pale in color
    • Contains keratotic squames

Differential diagnosis

Management

  • Wide surgical excision to avoid recurrence (significant recurrence rates)
  • Marsupialization
  • Curettage
  • Enucleation with application of Carnoy’s solution

Reasons for increased recurrence rate

  1. Thin fragile lining – difficult to enucleate intact
  2. Finger like cystic extensions into cancellous bone
  3. Presence of satellite/daughter cyst in cystic wall/capsule
  4. Formation of additional keratocysts from other rests of dental lamina
  5. Inferior standards of surgical treatment
  6. Possibly a neoplasm

Reasons it can be considered a neoplasm

  1. High recurrence rate
  2. Fast growth/aggressive behaviour
  3. Can invade adjacent tissues
  4. Possible malignant transformation
  5. Associated with mutated PTCH suppressor gene

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Follicular/ dentigerous cyst

Oral Pathology

Pushes tooth further into the jaw bone, therefore impacts tooth

Etiology

  • Impaction
  • Delayed eruption

Common site

  • Maxillary canine
  • Premolars
  • 3rd molars

Growth

  • Regular
  • Large
  • Buccal expansion

Peak age

  • 3-4th decade

Pathology

  • Split develops between REE and enamel

Radiology

  • Unilocular radiolucency surrounding crown

Histology

Cyst attached at amelocemental junction – surrounding crown of unerupted tooth

  • Cyst wall:
    • Derived from dental follicle
    • Thin, delicate ‘myxoid’/mucinous appearance
  • Epithelial lining:
    • Derived from REE
    • Mucous cells
    • Flat basement membrane – thin, uniform, non-keratinized, attached at amelocemental junction
    • No rete pegs
  • Lumen:
    • Eosinophilic serous exudate
    • Cholesterol cleft

Management

  • Surgical removal
  • Marsupialization (large)
  • Enucleation (small)

Recurrence

  • Rare

Differential diagnosis

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Radicular cyst & residual cyst

Oral Pathology
  • Affects any tooth
  • When small – symptomless
  • When large – expansion of alveolar bone + enlarge through sinus
  • Seldom pain, unless inflamed and abscess formation

Etiology

Pathology

  • Proliferation of rests cells of Malassez

Common site

  • Maxillary anterior teeth (12, 21)

Growth

  • Regular, limited, buccal expansion

Peak age

  • 4-5th decade

Clinical

  • Slow progressing painless swelling, no symptoms unless infected
  • Initial swelling is round
  • When bone reduced to eggshell thickness – crackling on pressure
  • When wall resorbed – soft fluctuant swelling, blue color, beneath mucous membrane

Radiology

Histology

  • Cyst wall:
    • Granulation tissue
    • Thick fibrous outer zone
    • Inflammatory cells infiltrate
    • Cholesterol clefts
    • Multinucleated giant cells
    • Vascular
  • Epithelial lining:
    • Non keratinized stratified squamous epithelium (absent in some places)
    • Hyperplastic
    • Arcading rete pegs
    • ± Goblet cells (mucous metaplasia)
    • Rushton bodies
  • Lumen:
    • Serous exudate (pale pink)
    • Macrophages (foamy)
    • Cholesterol clefts

Management

  • Non surgical: RCT
  • Surgical:
    • Enucleation (remove whole cyst)
    • Marsupialization (suture ends of cyst to external surface)
    • Decompression (small opening in cyst and drain)
    • Apicectomy (tooth’s root tip removed)

Recurrence

  • Rare
  • Residual cyst if retained after extraction of tooth

NB: Lateral type rare, Due to inflammation of pulp extending into lateral periodontium along lateral root canal

Residual cyst

  • 20% of radicular cyst – persists after extraction of causative tooth
  • Common cause of swelling in edentulous jaws in old people
  • Interferes with fitting of dentures but regresses spontaneously

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Paradental cysts of Craig

Oral Pathology

Common site

  • Mandible: buccally/ distobuccally placed
  • Rises along side of partially erupted 3rd molar + pericoronitis
  • Teeth associated with these cysts show enamel spur extending from buccal cervical margin to root furcation

Pathogenesis

  • Pericoronal inflammation
  • Proliferation of REE covering unerupted/ partially erupted part of crown of tooth/ buccal spur
  • Forms paradental cyst

Radiology

  • Well defined radiolucency:
    • Neck of tooth
    • Coronal 3rd of root

Management

  • Extraction

Picture

Orofacial cysts

Oral Pathology

Cysts of oro-maxillofacial region

Definition

  • Pathological cavity containing pus and fluid/ semi-fluid/ gas ± lined with epithelium

Classification

(I) Odontogenic cysts

1. Inflammatory (dental cysts)

2. Developmental

(II) Non odontogenic cysts

1. Fissural cysts

2. Bone cysts/pseudocysts

3. Soft tissue cysts

4. Maxillary antral cyst

  • Mucous retention cyst, extravasation cyst, pseudocyst
  • Mucosal lining of sinus, respiratory epithelium
  • Radiology: opaque dome shape
  • Picture

Pathogenesis

Source of epithelium

TypeEpithelium sourceRests originCyst
Odontogenic restsRests of MalassezEpithelial root sheath– Radicular cyst
Odontogenic restsReduced enamel epithelium (REE)Enamel organ– Paradental cyst
– Dentigerous cyst
– Eruption cyst
Odontogenic restsRests of dental lamina (Serres)Epithelial connection between mucosa and enamel organ– Lateral periodontal cyst
– Gingival cyst
– Odontogenic keratocyte
– Glandular cyst
Non odontogenic restsNasopalatine canal duct remnantsVestigial nasopalatine ducts– Nasopalatine cyst
Non odontogenic rests– Salivary duct epithelium
– Ductal epithelium in lymphoid tissue
– Thyroglossal duct epithelium		– Mucous retention cyst
– Branchial cyst
– Thyroglossal cyst
Cyst source of epithelium

Cyst initiation

Stimuli for cavitation and epithelial cell proliferation

Periapical abscess: Pus at root apex. Inflammation, pain, lymphadenitis, fever. Complication is acute osteomyelitis

Periapical granuloma: Chronic inflammation at apex of non vital tooth. Dull percussion sound, mild pain on chewing, feels elongated in socket. Well circumscribed ovoid radiolucency at apex <1cm

Inflammation

1. Necrotic/ infected pulp – periapical granuloma – inflammatory cells release cytokines – inflammatory cyst develops from rests of Malassez – Radicular cyst

2. Inflammation at base of periodontal pocket – lateral granuloma – lateral periodontal cyst in lateral root canals

  • Inflammatory cells secrete cytokines – IL-6, IL-1, TNF, growth factors (EGF, TGFβ, KGF) – stimulate epithelial cell proliferation
  • Plasma cell activity in inflammatory cysts – accumulation of gamma globulin – Russell bodies
  • Breakdown of hemorrhagic products – hyalin aggregates – Rushton bodies

(EGF – Epidermal GF, TGFβ – Transforming GFβ, KGF – Keratinocyte GF)

Developmental factors

  • Produce anti-apoptotic factors eg. Bcl2
  • High proliferative index of epithelium (+ve Ki67 staining)

Cyst expansion

Continued cyst growth and bone resorption

Hydrostatic mechanism – Process of dialysis

  • Cyst wall acts as semipermeable membrane
  • Proteins accumulate in cyst
  • Fluid accumulates due to osmotic gradient
  • Fluid accumulates as inflammatory exudate in cyst lumen
  • Creates +ve pressure in cyst + osmotic gradient for more fluid to accumulate
  • Expansion of inflammatory cysts and dentigerous cyst

Cytokines and PGE2 mediated bone resorption

  • Cyst produce proinflammatory cytokines – IL-1, TNF, PGE2 – potent inducers of bone resorption

Epithelial growth factors and mural growth

  • EGF, TGFβ – Proliferation of cyst epithelium

Mechanism of bone resorption: Radicular cyst

  • Bacterial antigens + irritants from necrotic pulp
  • Inflammation of cyst capsule
  • Chronic inflammatory cell infiltration
  • Cytokines release Eg. IL-6
  • Fibroblast activation
  • Collagenase, prostaglandins, osteoclast stimulation
  • Bone resorption

Investigations of cystic lesions of the jaws

1. Signs common to all cysts:

  • Dull sound on tooth percussion
  • Displaced teeth
  • Swelling
  • Eggshell crackling on pressure
  • Loosened teeth (late stage)
  • Fluctuation

2. Other signs:

  • Non vital tooth – inflammatory dental cyst
  • Unerupted tooth – dentigerous cyst

Specific histological features

Odontogenic inflammatory

1. Cholesterol clefts – Cholesterol crystals lost during tissue processing – slit like spaces in decalcified tissue sections

2. Rushton (hyalin) bodies – Common in inflammatory cysts

Odontogenic developmental

1. Cyst epithelium – Flat basement membrane

2. Mucous metaplasia – Most common in dentigerous cyst

Diagnosis for cystic lesions

1. Radiography:

  • Morphology of lesion
  • Relationship with teeth and other structures
  • Soft tissue cyst – inject contrast media

2. Incisional biopsy:

  • Extensive lesion that may not be a simple lesion
  • Cyst at angle of ramus of mandible – KCOT and ameloblastoma commonly occur

3. Aspiration biopsy:

Following observations made:

1. Appearance:

  • White sludgy material – Keratin of KCOT
  • Cannot withdraw any fluid – solid tumor mass/ viscous keratin content
  • Pus – infected cyst
  • Air – needle in maxillary antrum
  • Blood:
    • Contamination from needle wound
    • Central hemangioma
    • Aneurysmal bone cyst

2. Smell: Foul – infected

3. Culture: If infection suspected

4. Bilirubin content: Fluid from solitary bone cyst – clots on standing – high bilirubin content

5. Electrophoresis: Use normal serum as control

  • KCOT – no soluble protein band (most protein is insoluble keratin)
  • Inflammatory and dentigerous cyst – similar to serum
  • Infected/blood contaminated – similar to serum

6. Total soluble protein content:

  • KCOT < 4g/100ml
  • Others > 5g/100ml

7. Smear, fix and stain for keratin:

  • If keratinized squames seen – KCOT